The present invention relates to a paper sheet feeding apparatus, and particularly, although not exclusively, to the paper sheet feeding apparatus capable of feeding a stack of paper sheets into a paper sheet receiving part automatically and accurately one by one at regular intervals in a copying transmitting machine such as a facsimile machine or a photocopier.
Generally, if a transmitting signal is generated when a number of paper sheets are set in a paper sheet supply part, the paper sheet feeding apparatus of the copying transmitting machine begins to feed paper sheets from the lowest paper sheet one by one in order and transmits wanted information by scanning images of fed paper sheet.
Conventionally, in order to successively feed a number of paper sheets one by one, a device shown in FIG. 1 is used. A cylindrical automatic paper sheet feed roller 2, for feeding the paper sheets 1 set in a paper sheet supply part from a front edge of the paper sheet, is fixed at a middle of the paper sheet feed roller shaft 3 of the automatic paper sheet feed roller 2, and the paper sheet feed roller shaft 3 is supported at a frame 4 to be rotated. The paper sheet feed rubber 21 is selectively contacted with paper sheet feed roller 2 by a spring 22. An end of the paper sheet feed roller shaft 3 is got in a cylindrical part 5a of a bushing 5 to be fixed. A cylindrical part 7a of an automatic paper sheet feed gear 7 and the cylindrical part 5a of a blushing 5 are inserted into a clutch spring 6, the clutch spring 6 blocking or transferring a power applied to the paper sheet feed gear 7 from a motor ( not figured ) to the paper sheet feed roller 2.
A cylindrical transfer roller 8 which is positioned in paralleled with the automatic paper sheet feed roller 2 and transmits the paper sheets, is fixed at the middle of a transfer roller shaft 9 of the transfer roller 8, and the transfer roller shaft 9 is supported at the frame 4 to be rotated. A pinch roller 11 applying pressure to the transfer roller 8 is supported at another frame during the transferring of the paper sheet. A transfer gear 8a is fixed at an end of the transfer roller shaft 9 adjacent to the frame 4, delivering rotary power from the outside to the transfer roller 8.
If the paper sheet 1 is fed to the automatic paper sheet feed roller 2, the paper sheet feed gear 7 and transfer gear 8a turn in a direction of A. Accordingly, as shown in FIG. 3B, since the clutch spring 6 put between the cylindrical part 7a of the automatic paper sheet feed gear 7 and the cylindrical part 5a of the bushing 5, is compressed to a rotatable direction. The power applied to the automatic paper sheet feed gear 7 is transmitted, through the clutch spring 6 and the bushing 5, from the outside to the paper sheet feed roller shaft 3, thereby turning the paper sheet feed roller shaft 3 to the direction of A. By this rotation, the paper sheet 1 is transferred from the automatic paper sheet feed roller 2 to the transfer roller 8, as a paper sheet reader 23 begins to read the paper sheet from the front edge thereof. Next, the paper sheet 1 is introduced between a pinch roller 11 and the transfer roller 8 by a friction force, and then transferred with tension forced, which is caused by the fact the linear velocity of the automatic paper sheet feed roller 2 is slower than that of the transfer roller 8.
As the paper sheet 1 is transferred, the liner velocity of the paper sheet feed roller 2 approaches the linear velocity of the transfer roller 8. Between the rotary bushing 5 joined with the paper sheet feed roller shaft 3 and the automatic paper sheet feed gear 7 of a constant velocity is generated a phase traveling difference .DELTA.Q which is proportional to the length of the paper sheet 1. This phase traveling difference .DELTA.Q is caused by the velocity difference between the automatic paper sheet feed roller 2 and the automatic paper sheet feed gear 7. As a result, as shown in FIG. 3A, the compressed spring clutch 6 comes to loose gradually, forming a gap .DELTA.g between the outer circumferences of the cylindrical parts 5a and 7a and the inside circumference of the clutch spring 6, so that the automatic paper sheet feed roller 2 comes to turn at the same velocity with the linear velocity of the transfer roller 8.
On the other hand, if a back edge of the paper sheet 1 slips out of the automatic paper sheet feed roller 2, as shown in FIG. 3B, the automatic paper sheet feed gear 7 turns to the direction of A as much as the phase traveling difference, so that the clutch spring 6 surrounding the cylindrical part 7a of the automatic paper sheet feed gear 7 and the cylindrical part 5a of the bushing 5, is compressed toward the A-direction. The paper sheet feed gear 6 turns to the A-direction along with the paper sheet feed roller shaft 3. Thereby, the power from the exterior is delivered to the paper sheet feed roller shaft 3 of the automatic paper sheet feed roller 2 through the bushing 5, then the next paper sheet is supplied to the automatic paper sheet feed roller 2. That is, the phase traveling difference between bushing 5 and the paper sheet feed gear 7 makes a feed interval between the front edge of the paper sheet 1 and the back edge of the paper sheet, thus enabling the paper sheets to be fed one by one.
Accordingly, in the conventional paper sheet feed apparatus, in order to achieve the above-described operation, that is a role for blocking or transferring the external power of the automatic paper sheet feed gear 7 to the bushing 5, the clutch spring 6 must be delicately assembled so as to provide very small gap between the clutch spring 6 and the cylindrical parts 5a and 7a. As the assembling of such a clutch spring is not easy, however, an expert for assembling the clutch spring is needed, and moreover, using of the clutch spring brings about the raising of the cost.